Variable resistor with improved terminal



Sept. 13, 1955 A. M. DAILY ET AL VARIABLE RESISTOR WITH IMPROVEDTERMINAL Filed Jan. 11, 1954 United States Patent VARIABLE RESISTOR WITHIMPROVED TERMINAL Arthur M. Daily, Edwardshurg, Mich, and Joseph G.Veatch, Elkhart, Ind., assignors to Chicago Telephone gupplyCorporation, Elkhart, Ind., a corporation of Kin iana ApplicationJanuary 11, 1954, Serial No. 403,164-

1 Claim. (Cl. Mil-55) This invention relates broadly to variableelectrical resistors or volume controls of the type used in radio andtelevision apparatus and refers more particularly to the terminals forthe resistance elements of such controls.

The primary purpose of this invention is to provide an improved terminalfor such variable resistors which is not only better suited tomechanized or automatic assembly of the control, but also better adaptsthe control to use with printed circuitry.

To this end it is more specifically an object of this invention toprovide a terminal for the purpose described which is characterized bythe fact that it is essentially a cylindrical pin or stem having one endportion thereof received in and passing through aligned holes in theinsulated base of the control and the adjacent portion of the resistanceelement, and flanges integral with the pin or stem between which theoverlying portions of the base and resistance element are clamped.

Still another object of this invention is to provide an improvedterminal of the character described which is so designed that the heatimparted thereto during the soldering operation by which a lead issoldered to the terminal is effectively and quickly dissipated to assureagainst loosening of the terminal by the contending forces of expansionand contraction which might otherwise be set up in the base andterminal.

Still another object of this invention is to provide an improvedterminal of the character described which is more easily mounted inposition and which when mounted is more rigidly supported in a definiteposition than is the case with the conventional stamped and formed sheetmetal terminals heretofore widely used in variable resistors.

With the above and other objects in view, which will appear as thedescription proceeds, this invention resides in the novel construction,combination and arrangement of parts substantially as hereinafterdescribed and more particularly defined by the appended claim, it beingunderstood that such changes in the precise embodiment of thehereindisclosed invention may be made as come within the scope of theclaim.

The accompanying drawing illustrates two complete examples of thephysical embodiments of the invention constructed according to the bestmodes so far devised for the practical application of the principlesthereof, and in which:

Figure 1 is a side elevational view of a variable resistor embodyingthis invention and having parts thereof broken away and in section tobetter illustrate structural details;

Figure 2 is a perspective view of the variable resistor shown in Figure1, illustrating the same principally from the back end thereof;

Figure 3 is a perspective view of one form of the terminal per seillustrating the same prior to its assembly in the control;

Figure 4 is an enlarged detail sectional view through the mounted end ofthe terminal;

Figure 5 is a perspective view similar to Figure 3 but 2 ,2 E1943Patented Sept. 13, 1955 illustrating another form of terminal embodyingthis invention; and

Figure 6 is a fragmentary detail sectional view through a portion of avariable resistor base and its resistance element illustrating theterminal of Figure 5 mounted in position thereon.

Referring now particularly to the accompanying drawing, the numeral 5designates generally a variable resistor of the type having a fiat base6 of insulating material and a fiat split ringshaped resistance element7 on the inner face of the base. The resistance element 7 is adapted tobe traversed by a contactor which forms part of the rotating assembly ofthe control. This assembly, which is of conventional construction andhence not shown, is inside the housing of the control formed jointly bythe base 6 and a cup-shaped stamped metal cover or casing 8 and isdriven by a control shaft 9 which passes through the base 6.

The rotating assembly of the control in addition to the contactor whichtraverses the resistance element also has a contactor riding upon acollector ring (also not shown) which generally is provided with anintegral terminal iii which projects perpendicularly straight out fromthe front of the base or more correctly from a radially outwardlyextending terminal support 11 integral with the base.

The end portions 12 of the resistance element overlie the terminalsupport Ill and are secured thereto by means of the terminals 1?; ofthis invention. While the use of the terminals of the resistance elementto secure the element in place on the base is not new in itself, the wayin which this is done with the terminal 13 is new and has manyadvantages over the prior art. Thus for instance, by virtue of theirconstruction and mounting the terminals 15 have greater rigidity thanheretofore, and assurance against impairment of good electricalconnection between the terminal and the resistance element is increased.

Another very important advantage of the present invention lies in thefact that the terminals 13 are far better suited to mechanized assemblyand also by virtue of their added rigidity better adapt the control touse with printed circuitry.

in that form of the invention illustrated in Figures 1 to 4, inclusive,the terminals 13, which are of course identical in all respects, consistessentially of a cylindrical pin or stem having an inner end portion 14and an outer end portion 15 with a flange 16 integral with andseparating these two end portions. The flange 16 is undercut as at 17for a purpose to be later described, and the extremity of the endportion 14 has an axial well or cavity 18 extending axially thereinto.The end portion 14 fits snugly in aligned holes in the base and theadjacent end portion 12 of the resistance element with the flatunderside 19 of the flange 16 bearing against the outer face of the baseand more specifically its terminal support 11.

By virtue of the undercut formation of the flange the end portion 14 ofthe terminal may have a close fit in the holes in which it is receivedwithout interfering with the engagement of the fiat underside 19 of theflange with the face of the base against which it abuts.

After the terminal has been thus assembled, the hollow extremity of thestern portion 14 is rolled over or riveted .to form a second flange 2i?which overlies the surface of the resistance element and has goodelectrical connec tion therewith. The portions of the resistance elementand base immediately adjacent to the aligned holes in which the terminalis received are thus clamped between the two flanges, and to improve theelectrical connection between the terminal and the resistance elementthe flange 29 preferably has a plurality of radial indentations 21formed therein during the clinching or riveting operation, whichindentations as best shown in Figure 4, result in slight radiallyextending ridges 22 projecting from the underside of the flange Z9 andbiting into the adjacent surface of the resistance element.

The terminal 13 is thus rigidly and firmly mounted upon the base of thecontrol instrument and when thus positioned projects straight out fromthe front of the base in parallel relationship to the axis of thecontrol shaft 9. Accordingly, when the control is mounted upon a panel24 having printed wiring (not shown) on its front face, the terminals 13as well as the center terminal 10 will project through appropriatelylocated holes in the panel, to enable the terminals to be soldered inany suitable manner to their respective leads.

The heat imparted to the terminals 13 during the soldering operation isquickly dissipated by the relatively large area of contact between theflange 16 and the base 6 and as a result the effect of contending forcesof expan sion and contraction is minimized so that there is lesslikelihood of the terminal being loosened during the solderingoperation.

Attention is directed to the fact that the flange 16 has a diameterapproximately twice that of the stern portion 15 and that it hassubstantial thickness so as to have adequate strength to withstand theriveting or clinching operation by which the terminal is secured inplace.

in that embodiment of the invention illustrated in Figures 5 and thepreformed flange 16', which like the flange 16 is undercut as at 17', ison the extreme end of the mounting portion 34 so as to overlie theresistance element rather than the front face of the base. Also,

in this case the mounting portion 14 of the terminal is larger indiameter than its outer end portion 15 which provides the terminal perse so as to form a step or shoulder 25 spaced from the fiat underside19' of the flange 16' a distance suflicient to enable the attaching endportion 14' to reach all the Way through the aligned holes in theresistance element and base. During assembly the shoulder portion 25 isupset or swaged down over the adjacent face of the base to form thesecond flange 20.

As in the previously described embodiment of the invention, the terminalconstruction of Figures 5 and 6 also I has the advantage of rapidlydissipating the heat imparted to the terminal during the solderingoperation over a relatively wide area but in this case, of course, theflange 16 carries this heat into the resistance element rather thandirectly into the base.

From the foregoing description taken in connection with the accompanyingdrawing it will be readily apparent to those skilled in the art thatthis invention provides an improved terminal for variable resistorswherein the resistance element is secured in position on its base by theattachment of the terminal, and that the terminal of this invention hasthe advantage of lending itself well to mechanized assembly of thecontrol and of better adapting the control to use with printedcircuitry.

What we claim as our invention is:

in a variable resistor: a flat base of insulating material; a resistanceelement on the rear face of the base; a rotatable contacto. assemblybehind the base; a control shaft for the contactor assembly extendingtherefrom perpendicularly to the base and projecting through and beyondthe front face of the base; and rigid terminals for the resistance elemnt secured to the base and projecting perpen" arly t'o ardly therefromin parallel relation to t sh ft to pass through a panel upon which theresistor is mo ed with its shaft projecting through the panel, t. e pro,..tion of the terminals through the panel ding the resistor againstrotary motion about the shaft axis and providing for the connection ofthe resistance element to circuit leads printed on the front face of thepanel, said terminals each comprising a still stem having one endportion thereof received in aligned holes in the base and the adjacentend portion of the resistance element and its other end portionextending a substantial distance out from the overlying base andresistance element, nd flanges on the stern overlying the outer surfaceporti as of the base and the resistance element boundthe edges of theholes therein and between which the e and resistance element areclamped, to thereby effect good electrical connection between theterminals and the resistance element and also rigidly mount the erminalwith its other end portion projecting perpena arly outwardly from thebase; one of said flanges being a preformed integral part of the stem,and the other flange being a part of the stern which has been deformedfrom its original shape.

References Cited in the file of this patent UiJtTED STATES PATENTS1,874,594 Olson Aug. 30, 1932 2,157,428 Obszarny May 9, 1939 2,169,594Schellenger Aug. 15, 1939 FOREIGN PATENTS 1,028,657 France Nov. 30, 1950

